Dmitry Sokolov, 21, a prominent militant known to be the partner of the female suicide bomber who committed an attack in a bus in Volgograd in October, was killed along with four of his accomplices in a Makhachkala suburb on Saturday, the National Antiterrorist Committee(NAC) reported.

"The active phase of the operation has been completed, and five militants have been neutralized, among whom Dmitry Sokolov has been identified," the NAC said in a statement.

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None of the law enforcement officers or civilians was harmed, it said.

"During the negotiations, Sokolov claimed responsibility for terrorist attacks he committed, including the bombing of a bus in Volgograd. He said he had personally assembled the IED [improvised explosive device], which the female terrorist bomber later set off," it said.

"A woman and a child had been among the people blockaded in the house. It was suggested to the gunmen that they release them, lay down their arms and surrender to the authorities. Sokolov's mother was engaged in the negotiations that lasted many hours, and she talked to her son on the phone, but the gunmen refused to go out. As a result, it was possible to take the woman and the child out," the NAC said.

The information on Sokolov's presence in the community of Semender outside Makhachkala was obtained through "active operational and investigative measures in relation to the terrorist underworld acting in some regions of the Republic of Dagestan," the NAC said.

The head of the operational headquarters for Dagestan decided to assign the area counter-terrorist operation status, blockade the area and carry out the necessary regime measures on Saturday morning. "The necessary search and investigative operations are being conducted at the scene," the statement said.

A law enforcement source had told Interfax earlier that five gunmen had been killed in an operation in Makhachkala. "The active phase of the armed clash was finished at 1:45 p.m. Moscow time. Five militants have been killed, including the gunman and demolitionist Sokolov, who was a common-law husband of the Volgograd suicide bomber," the source said.

Three out of the five gunmen have been identified, the source said. A lot of weapons and ammunition were found at the scene.

A female suicide bomber set off an improvised explosive device in a bus in Volgograd on October 21. The attack killed six people and the bomber herself, who was later identified as Naida Asiyalova, and dozens were injured.

Head of the Investigative Committee department for Dagestan Mikhail Muzrayev said at a press conference on Nov. 7 that investigators pursued the theory of Asiyalova's partner Sokolov's role in the Volgograd bombing. "She met her common-law husband Dmitry Sokolov some three years ago. They were both into radical Islam," Muzrayev said.

He was reported as missing by his parents in summer 2012, Muzrayev said. The man's parents said their son had gone to a mosque and had never returned home, he said.

The investigators have examined Sokolov\'s biography and relations, Muzrayev said. In particular, he said Sokolov had studied in six schools because his father was a military man, graduated from school in Krasnoyarsk, and entered an aerospace college. In late 2009, he moved to the Moscow region, converted to Islam, and was admitted to the Moscow State Forestry University. However, he took a leave of absence two months later and then left the university.

Investigators also found out that Sokolov's Muslim name was Abduljabar, and his nickname was Giraffe.